Obesity contributes to the development of debilitating chronic health conditions in millions of Americans, underlies nearly 10 percent of all U.S. medical spending, and conservatively accounts for 30% of the gap in life expectancy between Americans and their counterparts in 13 other high-income countries. Despite tremendous investment in obesity treatment, little headway has been made. Of those who try, less than half succeed in losing a clinically significant amount of weight; few maintain weight loss; and adult obesity rates, currently 35.7% overall, have not declined. These disappointing outcomes challenge researchers and policymakers to consider how the residential environment can facilitate healthful eating and physical activity. Despite promising early research, there is no consensus about environmental contributors to body weight. To address this gap, the objective of the proposed study is to estimate the contributions of residential environment attributes (walkability, aesthetics, recreational places, healthy and unhealthy food availability, and prices for healthy and less healthy foods) to BMI and other diet-sensitive and physical activity-sensitive measures of metabolic risk (blood pressure, serum glucose, and lipids) among adults. Specific aims are: (1) Through a retrospective 10- year longitudinal nationwide study of over 1.3 million veterans, determine specific attributes of the residential environment that help individuals to maintain healthier BMI, BMI trajectory, and metabolic risk status; and (2) In over 200,000 veterans who participated in the MOVE! weight management program and a similar number of matched controls, determine the extent to which specific attributes of the residential environment help individuals lose weight at six months, maintain weight loss at 18 months, and achieve healthier BMI trajectory longer term (5 years). To achieve these aims, we will link data on veterans' health to public and proprietary data characterizing attributes of their residential environments and employ panel data statistical models that are robust to a broad class of potential sources of bias and reverse causality. We will use similar models with a matched control group derived through propensity score analysis to determine the moderating impact of environmental attributes on MOVE! program effectiveness. The proposed study is highly innovative because it draws on the largest sample and the broadest geographic coverage of any study to date. We will use unique electronic health data stores, information on precise residential location, and detailed and repeated measures of environmental attributes, allowing us to capture changes in the environment and residential location over time to examine effects on individuals' BMI and metabolic risk over periods up to 10 years, including determining whether environmental attributes moderate the effectiveness of a weight management intervention. This research is significant because it will provide the most robust evidence to date that is needed to formulate effective public health policies to eradicate obesity and because it has the potential to fundamentally transform weight management intervention approaches.